The Apple II was special because it was released in 1977 with bit-mapped color graphics and sound. The Apple Disk II disk drive was released in 1978. Being a few years early with an all-in-one computer with a fast disk drive, bit-mapped color graphics and sound gave the Apple II an edge over the others. Five years later, Commodore released the low cost Commodore 64, and Apple no longer had the edge in the 8-bit market, but did have significant market share.
Radio Shack TRS-80: 1977 mono-text (Z/80)
Commodore Pet: 1977 mono-text, VIC-20: 1981, Commodore 64: 1982, Amiga 1985
Atari 2600 game console: late 1977, Atari 400/800: 1979, Atari ST: 1985
Acorn System 75: 1979
ZX 80: 1980, ZX 81: 1981, Spectrum: 1982
CP/M operating system: 1973-74, S-100 bus: 1974, Altair: 1974
Those CP/M "business" machines, CP/M (Z80) and 80-column cards that you could plug into the Apple II, and then the IBM-PC was released in 1981.
Apple Lisa: 1983 mouse mono, Mac: 1984 mono 3 1/2" disk drive, 1985 AppleTalk networking